Yellow Field Peas Fare Well After Recent Lows
Most yellow field pea being grown in western Nebraska were at early vegetative stages (4th to 7th node or 1-5 leaf stages) during last week’s cold snap, but extensive damage is not expected due to the pea’s level of frost tolerance.
Field pea tolerance to frost during early stages of vegetative growth is partially due to the “hypogeal” germination nature of the crop. For plant species with hypogeal germination (e.g., field pea, lentil, chickpea), shoot germination occurs belowground. It is different from plant species with epigeal germination (e.g., soybeans and common beans) where shoot germination occurs aboveground and plants are sensitive to early season frost.
In pea, the growing point/cotyledons and 1st node remain with the seed below ground. During the first three weeks after planting, the 2nd and 3rd nodes usually stay belowground and act as axillary buds. Pea can withstand extremely low temperatures (19–23oF) between the 1st and 5th node stages (Figure 2), even in the absence of snow cover on plants.
If leaves are killed and the stem is wilted, new growth will emerge from underground axillary buds through the 5th node stage. When plants are insulated by snow, they can tolerate temperatures as low as 100F without much damage. If frost occurs when plants are at the 7th node stage or beyond (40-50 days after planting, depending on weather conditions), plants are not likely to survive because axillary bud initiation will not occur at this stage.
Patience is needed when accessing suspected freeze injury. It will take at least one week of favorable weather for any freeze injury to be identified. Thus, don’t make any decision after a cold spell until the scope of the problem can be fully accessed.
As always, before destroying any crop consult the appropriate parties (crop insurance provider, Farm Service Agency, crop consultant agronomist, or UNL Extension educator).
Frost tolerance in pea is a complex process like drought tolerance and depends on the duration of acclimation/declamation cycles. When temperature drop is gradual, cold-acclimated field pea seedlings can tolerate significantly lower temperatures than when the temperature drop is sudden and hits non-acclimated field pea seedlings.
These articles offer further details of frost tolerance in field peas.
Welbaum, G.E., D. Bian, D.R. Hill, R.L. Grayson, and M.K. Gunatilaka. 1997. Freezing tolerance, protein composition, and abscisic acid localization and content of pea epicotyl, shoot, and root tissue in response to temperature and water stress. J. Exp. Bot. 48:643-654
Meyer, D.W., and M. Badaruddin. 2001. Frost Tolerance of Ten Seeding Legume Species at Four Growth Stages. Crop Sci. 41:1838-1842